Pixel array substrate including flux structure layer for improving LED contact and method of manufacturing thereof

ABSTRACT

A pixel array substrate has a plurality of sub-pixel regions, wherein a pixel structure of an individual sub-pixel region includes a first signal line, a second signal line, a first contact pad, a second contact pad, a light-emitting diode, a first conductive structure, and a flux structure layer. The first contact pad and the second contact pad are respectively electrically connected with the first signal line and the second signal line. The light-emitting diode is disposed on the first contact pad. A portion of the first conductive structure is disposed between the first contact pad and a first electrode of the light-emitting diode. The flux structure layer partially surrounds the first conductive structure and the light-emitting diode. A top portion of the flux structure layer is higher than a top surface of the first electrode and is lower than a bottom surface of a light-emitting layer of the light-emitting diode.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of and claims the prioritybenefit of U.S. application Ser. No. 16/183,719, filed on Nov. 7, 2018,now allowed. The prior U.S. application Ser. No. 16/183,719 claims thepriority benefit of Taiwan application serial no. 106143799, filed onDec. 13, 2017. The entirety of each of the above-mentioned patentapplications is hereby incorporated by reference herein and made a partof specification.

BACKGROUND Technical Field

The invention relates to a pixel array substrate, and more particularly,to a pixel array substrate having a flux structure layer.

Description of Related Art

Currently, in common liquid crystal displays, the light-emitting diode(LED) plays the role of providing a backlight source, and can use aliquid crystal as a light switch. With the progress of science andtechnology, display technology has gradually changed from backlightingto self-luminescence. Micro-LED displays further have the advantages ofhigh brightness, low power consumption, high resolution and high colorsaturation.

However, there are still many technical bottlenecks to be overcome inthe development of micro-LED displays, among which the most important is“Mass Transfer” technology. Mass transfer technology is the technologytransferring micro light-emitting diodes from the growth substrate tothe pixel array substrate. Due to the simultaneous transfer of a largenumber of micro light-emitting diodes, the micro light-emitting diodealignment accuracy is particularly important. In the prior art, microlight-emitting diodes often shift during transposition, resulting inthat the micro light-emitting diodes on the pixel array substrate cannotfunction normally. Therefore, there is a need for a solution to theaforementioned problems.

SUMMARY

The invention provides a pixel array substrate which may increase theprobability that the micro light-emitting diodes are electricallyconnected with the contact pads correctly.

The invention provides a manufacturing method of a pixel array substratewhich may increase the probability that the micro light-emitting diodesare electrically connected with the contact pads correctly.

A pixel array substrate of the invention has a plurality of sub-pixelregions, wherein a pixel structure of an individual sub-pixel regionincludes a first signal line, a second signal line, a first contact pad,a second contact pad, a light-emitting diode, a first conductivestructure, and a flux structure layer. The first signal line and thesecond signal line are disposed on the substrate. The first contact padand the second contact pad are respectively electrically connected withthe first signal line and the second signal line. The light-emittingdiode is disposed on the first contact pad. The light-emitting diodeincludes a first semiconductor layer, a second semiconductor layer, alight-emitting layer, and a first electrode. The light-emitting layer isdisposed between the first semiconductor layer and the secondsemiconductor layer. The first electrode is disposed between the firstsemiconductor layer and the first contact pad. At least a portion of thefirst conductive structure is disposed between the first contact pad andthe first electrode. The flux structure layer at least partiallysurrounds the first conductive structure and the light-emitting diode ina projection direction perpendicular to the substrate. The fluxstructure layer has a top portion, and the top portion is higher than atop surface of the first electrode and is lower than a bottom surface ofthe light-emitting layer.

A manufacturing method of a pixel array substrate of the inventionincludes: providing a substrate having a plurality of sub-pixel regions,wherein each of the sub-pixel regions has a first contact pad and asecond contact pad thereon; forming a first conductive materialseparately on each of the first contact pads; forming a flux materiallayer on the substrate, and the flux material layer at least partiallycovers each of the first conductive materials, wherein the flux materiallayer has a softening temperature lower than the melting temperature ofthe first conductive material; disposing a plurality of light-emittingdiodes on the flux material layer, wherein the light-emitting diodesrespectively correspond to each of the first conductive materials oneach of the first contact pads; heating the substrate so as to bring theflux material layer to the softening temperature; heating the substrateto bring each of the first conductive materials to the meltingtemperature to form a first conductive structure. Each of the firstconductive structures is electrically connected with the first electrodeof a corresponding light-emitting diode, wherein each of the firstconductive structures is electrically connected with a correspondingfirst contact pad.

One of the objectives of the invention is to increase the probabilitythat the light-emitting diodes are electrically connected with thecontact pads correctly.

One of the objectives of the invention is to reduce the problem of lightreflections in the pixel area and further improve the display quality.

To make the aforementioned features and advantages of the invention morecomprehensible, several embodiments accompanied with drawings aredescribed in detail as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the disclosure, and are incorporated in and constitutea part of this specification. The drawings illustrate exemplaryembodiments of the disclosure and, together with the description, serveto explain the principles of the disclosure.

FIG. 1 is a schematic top view of a pixel array substrate according toan embodiment of the invention.

FIGS. 2A-2G are schematic cross-sectional views showing a manufacturingprocess of a pixel array substrate according to an embodiment of theinvention.

FIG. 3 is a schematic top view of a pixel array substrate according toan embodiment of the invention.

FIGS. 4A-4F are schematic cross-sectional views showing a manufacturingprocess of a pixel array substrate according to an embodiment of theinvention.

DESCRIPTION OF THE EMBODIMENTS

FIG. 1 is a schematic top view of a pixel array substrate 10 accordingto an embodiment of the invention. FIGS. 2A-2G are schematiccross-sectional views showing a manufacturing process of a pixel arraysubstrate according to an embodiment of the invention. For example,FIGS. 2A-2G are schematic views of the manufacturing process in view ofthe cross-section of line AA′ of FIG. 1. In FIG. 1, some components areomitted.

Referring to FIG. 1, the pixel array substrate 10 includes a substrate100. The substrate 100 has a sub-pixel region PX, and a pixel structureis disposed within the sub-pixel region PX. Although FIG. 1 shows onlyone sub-pixel region PX, the invention is not limited thereto. Thesubstrate 100 actually includes a plurality of sub-pixel regions PX. Therange of the single sub-pixel region PX is defined by two adjacenttransmission lines having the same function and two adjacent conductivewires having the same function, and the transmission lines and theconductive wires respectively extend along different directions. In thisembodiment, the range of the single sub-pixel region PX is defined bytwo adjacent scan lines SL, and two adjacent data lines DL.

Referring to both of FIG. 1 and FIG. 2G, the pixel structure on thesub-pixel region PX includes a switching element T, a first signal line110, a second signal line CL, a first contact pad P1 (shown in FIG. 2G),a second contact pad P2, a light-emitting diode L, a first conductivestructure 140 (shown in FIG. 2G), and a flux structure layer 150.

The switching element T is disposed on the substrate 100 and includes agate G, a channel layer M, a source S, and a drain D. A gate insulatinglayer (not shown) is sandwiched between the gate G and the channel layerM, and the gate G is electrically connected with the scan line SL. Inthis embodiment, the gate G and the corresponding scan line SL areintegrally formed, but the invention is not limited thereto. The sourceS and the drain D are electrically connected with the channel layer M.The source S is electrically connected with the data line DL. Althoughthe switching element T takes a bottom-gate thin film transistor inwhich the gate G is disposed between the channel layer M and thesubstrate 100 as an example in this embodiment, the invention is notlimited thereto. The switching element T may also be a top-gate thinfilm transistor in which the channel layer M is disposed between thegate G and the substrate 100 or another type of switching element.

The first signal line 110 and the second signal line CL are disposed onthe substrate 100. In this embodiment, the second signal line CL and thescan line SL may be the same film layer, and formed under the samepatterning process. However, the invention is not limited thereto. Thesecond signal line CL may also be other additional conductive filmlayers. The first signal line 110 is electrically connected with thedrain D. In some embodiments, the first signal line 110 and the drain Dmay also be the same film layer, and formed under the same patterningprocess. The first contact pad P1 (shown in FIG. 2G) and the secondcontact pad P2 are respectively electrically connected with the firstsignal line 110 and the second signal line CL. The first contact pad P1and the second contact pad P2 may be formed under the same or differentpatterning process.

Referring to FIG. 2G, a light-emitting diode L is disposed on the firstcontact pad P1. The light-emitting diode L includes a firstsemiconductor layer 320, a second semiconductor layer 340, alight-emitting layer 330, a first electrode 310, and a second electrode350.

Referring to FIG. 2A first, the first signal line 110 and the secondsignal line CL are disposed on the substrate 100, and an insulatinglayer 130 covers the first signal line 110 and the second signal lineCL. The first signal line 110 and the second signal line CL arerespectively electrically connected with the first contact pad P1 andthe second contact pad P2 through the openings in the insulating layer130. In some embodiments, there may be other insulating layers betweenthe first signal line 110 and the substrate 100 and/or between thesecond signal line CL and the substrate 100. The invention does notlimit the first signal line 110 and the second signal line CL to be indirect contact with the substrate 100. In some embodiments, there may beother insulating layers between the first signal line 110 and theinsulating layer 130 and/or between the second signal line CL and theinsulating layer 130. The invention does not limit the first signal line110 and the second signal line CL to be in direct contact with theinsulating layer 130. In some embodiments, the first signal line 110 andthe second signal line CL may be formed in different processes. That is,the first signal line 110 and the second signal line CL may respectivelybelong to different conductive film layers.

A first conductive material 140 a is separately formed on each of thefirst contact pads P1. The methods of forming the first conductivematerial 140 a includes, for example, solder plating, printing or othersuitable methods.

Referring to FIG. 2B, a flux material layer 150 a is formed on thesubstrate 100, and the flux material layer 150 a at least partiallycovers the first conductive material 140 a, wherein the softeningtemperature of the flux material layer 150 a is lower than the meltingtemperature of the first conductive material 140 a.

Referring to FIG. 2C, a patterning process is performed on the fluxmaterial layer 150 a, and the remaining flux material layer 150 b is notoverlapping with each other the second contact pad P2. In someembodiments, the method of performing the patterning process on the fluxmaterial layer 150 a includes a lithography process and an etchingprocess, but the invention is not limited thereto. In some embodiments,the flux material layer 150 a includes a photosensitive polymermaterial, and the flux material layer 150 a can be patterned without anadditional etching process.

Referring to FIG. 2D and FIG. 2E, a plurality of the light-emittingdiodes L are disposed on the flux material layer 150 b. Thelight-emitting diodes L respectively correspond to the first conductivematerial 140 a on the first contact pad P1.

The light-emitting diode L includes a first electrode 310, a firstsemiconductor layer 320, a light-emitting layer 330, a secondsemiconductor layer 340, and a second electrode 350. In this embodiment,the first electrode 310, the first semiconductor layer 320, thelight-emitting layer 330, the second semiconductor layer 340, and thesecond electrode 350 are sequentially stacked. The first electrode 310is disposed on the first semiconductor layer 320. The light-emittinglayer 330 is disposed between the first semiconductor layer 320 and thesecond semiconductor layer 340. The second electrode 350 is disposed ona side of the second semiconductor layer 340 opposite to thelight-emitting layer 330, and the second semiconductor layer 340 isdisposed between the second electrode 350 and the light-emitting layer330. An insulating layer 360 covers the side surfaces of the firstelectrode 310, the first semiconductor layer 320, the light-emittinglayer 330, the second semiconductor layer 340, and the second electrode350.

In this embodiment, the light-emitting diode L is, for example, formedon a growth substrate (not shown). Next, the light-emitting diode L islifted from the growth substrate by a pickup array 200, and then thelight-emitting diode L is transferred onto the first contact pad P1. Insome embodiments, after the light-emitting diode L is lifted from thegrowth substrate, and before the light-emitting diode L is transferredonto the first contact pad P1, the light-emitting diode L is transferredonto other transitional substrate. In some embodiments, the method oflifting the light-emitting diode L from the growth substrate by thepickup array 200 includes using electrostatic, Van der Waals forces orvacuum attraction. In some embodiments, the pickup array 200 lifts thelight-emitting diode L from the growth substrate by Van der Waalsforces, and the material of the pickup array 200 includespolydimethylsiloxane.

In some embodiments, the flux material layer 150 b is sticky, and mayassist the light-emitting diode L to be fixed and improve the contactbetween the light-emitting diode L and the first conductive material 140a. In some embodiments, the flux material layer 150 b is sticky at a lowtemperature (e.g. 0 to 60° C.). Therefore, the light-emitting diode Lmay be stuck on the first conductive material 140 a without the need toheat the flux material layer 150 b. Since no additional heating isrequired, the pickup array 200 will not thermally expand when thelight-emitting diode L is placed, and the alignment of thelight-emitting diode L will not fail due to the mismatch between thethermal expansion coefficient of the pickup array 200 and the thermalexpansion coefficient of the substrate 100.

Referring to FIG. 2F, the substrate 100 is heated to bring the fluxmaterial layer 150 b to the softening temperature. The substrate 100 isheated to bring the first conductive material 140 a to the meltingtemperature. The first conductive structure 140 and the flux structurelayer 150 are formed after cooling. In some embodiments, the fluxstructure layer 150 includes a resin acid, an abietic resin, and aphotosensitive polymer or a thermal curable polymer material. In someembodiments, the perpendicular projection area of the flux structurelayer 150 on the substrate 100 is slightly smaller than theperpendicular projection area of the flux material layer 150 b on thesubstrate 100. In some embodiments, after the flux material layer 150 bis heated, a plurality of organic acids such as resin acids or abieticacids are derived. Such organic acids have activity able to dissolve andremove metal oxides at a high temperature, and is presented as aninactive solid acid at normal temperature and humidity, having a verygood safety and reliability.

The first conductive structure 140 is electrically connected with thefirst electrode 310 of the corresponding light-emitting diode L. Thefirst conductive structure 140 is electrically connected with thecorresponding first contact pad P1.

The first electrode 310 is disposed between the first semiconductorlayer 320 and the first contact pad P1. At least a portion of the firstconductive structure 140 is disposed between the first contact pad P1and the first electrode 310. The flux structure layer 150 at leastpartially surrounds the first conductive structure 140 and thelight-emitting diode L in the projection direction perpendicular to thesubstrate 100. In other words, the orthographic projection of the fluxstructure layer 150 on the substrate 100 at least partially surroundsthe orthographic projections of the first conductive structure 140 andthe light-emitting diode L on the substrate 100. In this embodiment, abottom surface BS of the light-emitting layer 330 of the light-emittingdiode L contacts, for example, with a first surface of the firstsemiconductor layer 320, a top surface TS of the first electrode 310contacts, for example, with a second surface of the first semiconductorlayer 320. The flux structure layer 150 has a top portion TP, and thetop portion TP of the flux structure layer 150 is higher than the topsurface TS of the first electrode 310 and is lower than the bottomsurface BS of the light-emitting layer 330. In some embodiments, theheight difference X between the top portion TP of the flux structurelayer 150 and the bottom surface BS of the light-emitting layer 330relative to the substrate 100 is greater than 0.2 μm. In other words,the height difference X between the top portion TP of the flux structurelayer 150 and the bottom surface BS of the light-emitting layer 330 inthe direction PD perpendicular to the substrate 10 is greater than 0.2μm so that the fixed adhesion effect of the light-emitting diode L isimproved and the light extraction efficiency of the light-emitting diodeL is not affected by the flux structure layer 150. Therefore, thelight-emitting diode L has better light extraction efficiency.

Referring to FIG. 2G, a second conductive structure 120 is formed on thesubstrate 100. The second electrode 350 and the second conductivestructure 120 are connected with each other, and the second electrode350 is electrically connected with the second contact pad P2 by thesecond conductive structure 120. In this embodiment, the flux structurelayer 150 and the second contact pad P2 do not overlap with each otherin the projection direction perpendicular to the substrate 100. In otherwords, the orthographic projection of the flux structure layer 150 onthe substrate 100 and the orthographic projection of the second contactpad P2 on the substrate 100 do not overlap with each other. Therefore,it is possible to prevent the flux material from remaining on the secondcontact pad P2 to further cause the problem that the second conductivestructure 120 cannot be electrically connected with the second contactpad P2.

FIG. 3 is a schematic top view of a pixel array substrate according toan embodiment of the invention. It should be noted, the embodiment ofFIG. 3 follows the reference numbers and some contents of the embodimentof FIG. 1, wherein the same or similar reference numbers are used todesignate the same or similar elements, and the descriptions of the sametechnical contents are omitted. Reference may be made to the foregoingembodiments for the description of the omitted portions, and details arenot repeated herein.

The difference between the embodiment of FIG. 3 and the embodiment ofFIG. 1 is: in the pixel array substrate 20 in FIG. 3, the area of theflux structure layer 150 of the single sub-pixel region PX is larger.The flux structure layer 150 with this larger area can reduce theproblem of light reflections in the pixel area and further improve thedisplay quality and also may be served as a protective layer of theunderlying elements.

In this embodiment, the flux structure layer 150 has an opening OP so asnot to overlap with the second contact pad P2 in the projectiondirection perpendicular to the substrate 100. The second contact pad P2has a first outer contour, and the opening OP of the flux structurelayer 150 has a second outer contour. The shortest distance between thefirst outer contour and the second outer contour needs to be at leastgreater than 1 μm, thus avoiding the problem that the second contact padP2 overlaps with the flux structure layer 150 due to process errors.

According to the embodiment of FIG. 3 and the embodiment of FIG. 1, theperpendicular projection area of one sub-pixel region PX on thesubstrate 100 is B, the perpendicular projection area of the fluxstructure layer 150 in the single sub-pixel region PX on the substrate100 is A, wherein if the area A of the flux structure layer 150 isgreater than 0.05B, the basic auxiliary fixing property of the fluxstructure layer 150 can be achieved. The larger the area of the fluxstructure layer 150, the better the effect of reducing the problem oflight reflections in the pixel area. The flux structure layer 150 withthis larger area may further improve the display quality and may also beserved as a protective layer of the underlying elements. However, theproblem that the second contact pad P2 overlaps with the flux structurelayer 150 and the like due to process errors should be avoided so whenthe area A of the flux structure layer 150 is smaller than 0.916B, theoverall benefit is better.

FIGS. 4A-4F are schematic cross-sectional views showing a manufacturingprocess of a pixel array substrate 30 according to an embodiment of theinvention. The embodiment of FIGS. 4A-4F follows the reference numbersand some contents of the embodiment of FIGS. 2A-2G, wherein the same orsimilar reference numbers are used to designate the same or similarelements, and the descriptions of the same technical contents areomitted. Reference may be made to the foregoing embodiments for thedescription of the omitted portions, and details are not repeatedherein.

Referring to FIG. 4A first, the first signal line 110 and the secondsignal line CL are disposed on the substrate 100, and an insulatinglayer 130 covers the first signal line 110 and the second signal lineCL. The first signal line 110 and the second signal line CL arerespectively electrically connected with the first contact pad P1 andthe second contact pad P2 through the openings in the insulating layer130.

A first conductive material 140Aa is separately formed on each of thefirst contact pads P1, and a second conductive material 140Ba isseparately formed on each of the second contact pads P2. In someembodiments, the thickness of the second conductive material 140Ba isgreater than the thickness of the first conductive material 140Aa. Themethods of forming the first conductive material 140Aa and the secondconductive material 140Ba includes, for example, solder plating,printing or other suitable methods. In some embodiments, the formationof the first conductive material 140Aa, and the formation of the secondconductive material 140Ba are performed in the same step. The firstconductive material 140Aa and the second conductive material 140Bainclude, for example, the same material.

Referring to FIG. 4B, a flux material layer 150 a is formed on thesubstrate 100, and the flux material layer 150 a at least partiallycovers the first conductive material 140Aa. In this embodiment, the fluxmaterial layer 150 a surrounds the sides of the second conductivematerial 140Ba, and exposes at least a portion of the upper surface ofthe second conductive material 140Ba. In addition, in some embodiments,the flux material layer 150 a may also be adjacent to the secondconductive material 140Ba without covering the second conductivematerial 140Ba. The softening temperature of the flux material layer 150a is lower than the melting temperature of the first conductive material140Aa and the second conductive material 140Ba. In this embodiment, thethickness of the flux material layer 150 a is smaller than the thicknessof the second conductive material 140Ba, but the invention is notlimited thereto. In some embodiments, the thickness of the flux materiallayer 150 a is greater than the thickness of the second conductivematerial 140Ba.

Referring to FIG. 4C, a patterning process is performed on the fluxmaterial layer 150 a. In some embodiments, the method of performing thepatterning process on the flux material layer 150 a includes alithography process and an etching process, but the invention is notlimited thereto. In some embodiments, the flux material layer 150 aincludes a photosensitive polymer material, and the flux material layer150 a can be patterned with only a lithography process.

Referring to FIG. 4D and FIG. 4E, a plurality of the light-emittingdiodes L are disposed on the flux material layer 150 b. Thelight-emitting diode L includes a first electrode 310, a firstsemiconductor layer 320, a light-emitting layer 330, a secondsemiconductor layer 340, and a second electrode 350. The first electrode310 is disposed on the first semiconductor layer 320. The light-emittinglayer 330 is disposed between the first semiconductor layer 320 and thesecond semiconductor layer 340. The second electrode 350 is disposed onthe second semiconductor layer 340, and the second electrode 350 and thelight-emitting layer 330 are disposed on the same surface of the secondsemiconductor layer 340 and separated from each other. Therefore, inthis embodiment, the first electrode 310 and the second electrode 350are disposed on the same side of the light-emitting diode L andseparated from each other. An insulating layer 360 covers the sides ofthe first semiconductor layer 320, the light-emitting layer 330, and thesecond semiconductor layer 340. The first electrode 310, and the secondelectrode 350 of the light-emitting diode L respectively correspond tothe first conductive material 140Aa on the first contact pad P1 and thesecond conductive material 140Ba on the second contact pad P2.

In this embodiment, the light-emitting diode L is, for example, formedon a growth substrate (not shown). Next, the light-emitting diode L islifted from the growth substrate by a pickup array 200, and then istransposed on the first contact pad P1. In some embodiments, after thelight-emitting diode L is lifted from the growth substrate, and beforethe light-emitting diode L is transposed on the first contact pad P1,the light-emitting diode L may be transposed on the first contact pad P1after the light-emitting diode L is transposed on other transitionalsubstrates. In some embodiments, the method of lifting thelight-emitting diode L from the growth substrate by the pickup array 200includes using electrostatic, Van der Waals forces or vacuum attraction.In some embodiments, the pickup array 200 lifts the light-emitting diodeL from the growth substrate by Van der Waals forces, and the material ofthe pickup array 200 includes polydimethylsiloxane.

In some embodiments, the flux material layer 150 b is sticky, and mayassist the light-emitting diode L to be fixed and improve the adhesionbetween the light-emitting diode L and the first conductive material140Aa. In other words, the light-emitting diode L may first betemporarily adhered and fixed above the first conductive material 140Aa,wherein the fixation is not limited to being completely fixed, but mayalso be a state in which it is relatively less likely to slide.

Referring to FIG. 4F, the substrate 100 is heated to bring the fluxmaterial layer 150 b to the softening temperature. The substrate 100 isheated to bring the first conductive material 140Aa and the secondconductive structure 140Ba to the melting temperature. The firstconductive structure 140A, the second conductive structure 140B and theflux structure layer 150 are formed after cooling. In some embodiments,the flux structure layer 150 includes a resin acid, an abietic resin,and a photosensitive polymer or a thermal curable polymer material. Insome embodiments, the area of the flux structure layer 150 is slightlysmaller than the area of the flux material layer 150 b. A portion of theflux structure layer 150 is formed between the first conductive material140Aa (or the first conductive structure 140A) and the second conductivematerial 140Ba (or the second conductive structure 140B), and mayfurther prevent short-circuiting between the first conductive structure140A connected with the first contact pad P1 and the second conductivestructure 140B connected with the second contact pad P2.

The first conductive structure 140A is electrically connected with thefirst electrode 310 of the corresponding light-emitting diode L and thefirst contact pad P1. The first conductive structure 140A is, forexample, directly connected with the first electrode 310. The secondconductive structure 140B is electrically connected with the secondelectrode 350 of the corresponding light-emitting diode L and the secondcontact pad P2. The second conductive structure 140B is, for example,directly connected with the second electrode 350.

The first electrode 310 is disposed between the first semiconductorlayer 320 and the first contact pad P1. The second electrode 350 isdisposed between the second semiconductor layer 340 and the secondcontact pad P2. At least a portion of the first conductive structure140A is disposed between the first contact pad P1 and the firstelectrode 310. At least a portion of the second conductive structure140B is disposed between the second contact pad P2 and the secondelectrode 350.

The flux structure layer 150 at least partially surrounds the firstconductive structure 140A, the second conductive structure 140B and thelight-emitting diode L in the projection direction perpendicular to thesubstrate 100. In other words, the orthographic projection of the fluxstructure layer 150 on the substrate 100 at least partially surroundsthe orthographic projections of the first conductive structure 140A, thesecond conductive structure 140B and the light-emitting diode L on thesubstrate 100. In this embodiment, a bottom surface BS of thelight-emitting layer 330 of the light-emitting diode L contacts, forexample, with a first surface of the first semiconductor layer 320, anda top surface TS of the first electrode 310 contacts, for example, witha second surface of the first semiconductor layer 320. The fluxstructure layer 150 has a top portion TP, and the top portion TP ishigher than the top surface TS of the first electrode 310 and is lowerthan the bottom surface BS of the light-emitting layer 330. In someembodiments, the height difference X between the top portion TP of theflux structure layer 150 and the bottom surface BS of the light-emittinglayer 330 relative to the substrate 100 is greater than 0.2 μm. In otherwords, the height difference X between the top portion TP of the fluxstructure layer 150 and the bottom surface BS of the light-emittinglayer 330 in the direction PD perpendicular to the substrate 10 isgreater than 0.2 μm so that the fixed adhesion effect of thelight-emitting diode L is improved and the light extraction efficiencyof the light-emitting diode L is not affected by the flux structurelayer 150. Therefore, the light-emitting diode L has better lightextraction efficiency.

To sum up, the pixel array substrate in some embodiments of theinvention can increase the probability that the light-emitting diodesare electrically connected with the contact pads correctly and maintaingood light extraction efficiency. The pixel array substrate in someembodiments of the invention can reduce the problem of light reflectionsin the pixel area and further improve the display quality.

The pixel array substrate in some embodiments of the invention canprevent the flux material layer from remaining on the contact pads thatmay further cause the problem that the contact pads is not electricallyconnected with the conductive structure. The pixel array substrate insome embodiments of the invention can pattern the flux material layerwithout an additional etching process.

Although the disclosure has been described with reference to the aboveembodiments, it will be apparent to one of ordinary skill in the artthat modifications to the described embodiments may be made withoutdeparting from the spirit of the invention. Accordingly, the scope ofthe invention will be defined by the attached claims and not by theabove detailed descriptions.

What is claimed is:
 1. A manufacturing method of a pixel arraysubstrate, comprising: providing a substrate having a plurality ofsub-pixel regions, wherein each of the sub-pixel regions has a firstcontact pad and a second contact pad thereon; forming first conductivematerials separately on each of first contact pads; forming a fluxmaterial layer on the substrate, the flux material layer at leastpartially covering each of the first conductive materials, wherein theflux material layer has a softening temperature lower than a meltingtemperature of the first conductive materials; disposing a plurality oflight-emitting diodes on the flux material layer, wherein the pluralityof light-emitting diodes respectively correspond to each of the firstconductive materials on each of the first contact pads; heating thesubstrate to bring the flux material layer to the softening temperature;and heating the substrate to bring each of the first conductivematerials to the melting temperature to form first conductivestructures, each of the first conductive structures electricallyconnected with a first electrode of a corresponding light-emitting diodeof the plurality of light-emitting diodes, wherein each of the firstconductive structures is electrically connected with a correspondingfirst contact pad.
 2. The manufacturing method of a pixel arraysubstrate according to claim 1, wherein each of the plurality oflight-emitting diodes comprises: a first semiconductor layer and asecond semiconductor layer, wherein the first electrode is disposedbetween the first semiconductor layer and the first contact pad; alight-emitting layer disposed between the first semiconductor layer andthe second semiconductor layer; and a second electrode disposed betweenthe second semiconductor layer and the second contact pad.
 3. Themanufacturing method of a pixel array substrate according to claim 1,wherein in the step of disposing the plurality of light-emitting diodes,the flux material layer fixes each of the plurality of light-emittingdiodes on each of the first conductive materials.
 4. The manufacturingmethod of a pixel array substrate according to claim 1, wherein themethod of forming the flux material layer on the substrate comprisespatterning the flux material layer.
 5. The manufacturing method of apixel array substrate according to claim 2, further comprising: formingsecond conductive materials separately on each of second electrodes toelectrically connect the second electrodes with the second contact pads.6. The manufacturing method of a pixel array substrate according toclaim 2, wherein the second electrode of each of the plurality oflight-emitting diodes is disposed on the second semiconductor layer, andthe first electrode and the second electrode of each of the plurality oflight-emitting diodes are disposed on the same side of the secondsemiconductor layer and separated from each other, wherein themanufacturing method of a pixel array substrate further comprises:forming second conductive materials separately on each of second contactpads to electrically connect second electrodes with the second contactpads.
 7. The manufacturing method of a pixel array substrate accordingto claim 6, wherein forming the first conductive materials and formingthe second conductive materials are performed in the same step.
 8. Themanufacturing method of a pixel array substrate according to claim 6,wherein a portion of the flux material layer is formed between the firstconductive materials and the second conductive materials.
 9. Themanufacturing method of a pixel array substrate according to claim 1,wherein the flux material layer does not overlap with the second contactpad in the projection direction perpendicular to the substrate.
 10. Themanufacturing method of a pixel array substrate according to claim 9,wherein the flux material layer has an opening corresponding to thesecond contact pad, the second contact pad has a first outer contour,the opening of the flux structure layer has a second outer contour, andthere is a shortest distance between the first outer contour and thesecond outer contour, the shortest distance is greater than 1 μm.